I've done a bit of research into recent sightings of Red Kites in northern France, and basically there aren't any. There have been, however, a couple of extra-limital Black Kites in Brittany and Normandy. Therefore, odd though it sounds, it seems quite likely that only the latter have crossed the Channel, while the Reds have not. If anyone is interested in my speculations, take a look at the 21st May entry on www.kjhall.org.uk/lponews.htm. May all be nonsense, of course ……
I think the Red Kites are almost certainly wandering non-breeders from the UK with a population now around 1600prs. When we get high pressure in April-June many go for a wander. In Devon (where not yet breeding) we’ve been getting these influxes for a number of years, corresponding to the rising UK population. But have they crossed the channel and come back? I think not. The SW end of Cornwall just concentrates the wandering birds that have come down through the SW including Devon and can go no further. With this last event when high pressure became established, Devon was already seeing reasonable numbers heading west from the 14th, with multiple records of up to nine birds, which carried on through the 15th – as this was very broad front we do not know how many came through. Then bingo on the 16th they’ve got as far as they can go in west Cornwall and the big concentration. Interestingly Mike Langman was at Marazion on the 15th and had a number of birds heading west. But what’s really interesting is although there are few Black Kites mixed in in west Cornwall, hinting at a continental origin, on the Scillies they just had a couple Black Kites. If the Reds were coming off the continent they would be out numbering Blacks there too. The Brittany observations further back this up. Of course once they reach the end of Cornwall they all come wandering back heading east. It happened in June 2011 (see http://www.swopticsphoto.com/2011/06/red-kite-influx-in-west-cornwall.html) and earlier in other years.
Thanks for your comments, which are very helpful. I had seen the swopticsphoto page as part of my investigations, and some of the images there also show birds with some retained juvenile plumage characteristics, further emphasising that these birds are mostly sub-adults. It's particularly interesting that at least some birds in Devon have been seen heading west. This has always been a bit of a problem in sorting out what is going on, as the majority of those seen in Somerset and Avon over the years have been heading north and east, but not going the other way, making a continental origin seem more likely. But, as I said, the Red Kite remains a rarity in north-west France, and it's unlikely that such a raptor would choose to cross the Bay of Biscay direct from Spain, assuming that that many were wintering so far south, avoiding France altogether. The fact that only Black Kites were seen on the Scillies further adds to the evidence. I still also think that dispersing birds may circle up much higher than purposeful migrants, but maybe that's a speculation too far!
Six years ago when I lived in Normandy it was not rare to see Red Kite in May and October but none breeding anywhere that I knew of. This year travelling from Portugal to St Malo in April I saw Red Kite most days including north coast of Brittany. Saw far fewer on the same trek last year.
